You may need to email the authors of this article for the Stata codes since they claim to have used Stata 13 for the analysis Article Threshold effects of inflation on growth in the ASEAN-5 coun...
Yes, there are Stata codes for Panel Smooth Transition Regression (PSTR) Model. You can find the code for PSTR in the following research paper by González, A., Teräsvirta, T., & Dijk, D. v. (2005). Panel Smooth Transition Regression Models.